Secondary brain abscess following simple renal cyst infection: a case report
© Akuzawa et al.; licensee BioMed Central Ltd. 2014
Received: 24 February 2014
Accepted: 12 June 2014
Published: 16 June 2014
Escherichia coli (E. coli) is the most common causative bacteria of neonatal meningitis, but hematogenous intracranial E. coli infection is rare in adults. Moreover, intracranial abscess formation owing to E. coli, including brain abscesses and subdural empyema formation, is extremely rare. We herein present a case involving a patient with a brain abscess owing to E. coli following a simple renal cyst infection. A review of the literature is also presented.
A 77-year-old Japanese woman with a history of polymyalgia rheumatica was admitted to our hospital because of persistent fever, right flank pain, and pyuria. Intravenous antibiotics were administered; however, her level of consciousness deteriorated 6 days after admission. Contrast-enhanced magnetic resonance imaging showed a brain abscess in the left occipital lobe and pyogenic ventriculitis. Enhanced abdominal computed tomography revealed a right renal cyst with heterogeneous content. Culture of urine, blood, and aspirated pus from the infected cyst revealed E. coli with identical antibiotic sensitivity in all sites, suggesting that the cyst infection and subsequent bacteremia might have caused the brain abscess. The patient recovered after a 6-week course of meropenem.
The prognosis of patients with E. coli-associated intracranial abscess is usually poor. Advanced age and immunosuppression may be potent risk factors for intracranial abscess formation owing to the hematogenous spread of E. coli.
KeywordsBacteremia Brain abscess Escherichia coli Simple renal cyst
Although brain abscesses are relatively uncommon, they remain potentially fatal central nervous system (CNS) infections despite the evolution of neurosurgical techniques, new antibiotics, and new imaging technologies. Brain abscesses are usually caused by contiguous infections such as sinusitis or middle ear infections; however, hematogenous spread of pyogenic pathogens from remote-organ infections can also cause brain abscesses .
The clinical signs of brain abscesses are nonspecific. The most common symptoms are reportedly headache and fever, but the classical triad of fever, headache, and nausea is seen in up to 20% of patients . Focal neurological deficits are reportedly recognized in 57% of patients . Additionally, laboratory findings may show a normal white blood cell (WBC) count or C-reactive protein (CRP) level . Thus, early imaging studies including enhanced brain computed tomography (CT) or magnetic resonance imaging (MRI) are of cardinal importance for a definitive diagnosis and appropriate treatment in the early period [1, 2].
We herein present a rare adult case of a left occipital lobe brain abscess that likely resulted from the hematogenous spread of an Escherichia coli (E. coli) right renal cyst infection followed by formation of pyogenic intraventricular empyema.
A 77-year-old Japanese woman was admitted to our hospital because of fever of unknown origin. She had developed general fatigue and a slight fever 2 weeks before admission. Headache and a fever higher than 38°C had developed 3 days before admission, and oral cefditoren pivoxil prescribed at another hospital had been ineffective. She had a 2-year history of polymyalgia rheumatica and chronic gastritis. She had initially been treated with 15 mg/day of prednisolone for the polymyalgia rheumatica. Her dosage of prednisolone was tapered with improvement of her symptoms, and she had been treated with prednisolone (5 mg/day) and famotidine (20 mg/day) for 1 year before admission. She had no other medical or family history and did not smoke or drink alcohol. Physical examination on admission revealed a height of 156 cm, weight of 49 kg, temperature of 40.2°C, heart rate of 120 beats/min, and blood pressure of 116/62 mmHg. No obvious abnormalities of the chest or abdomen were found with the exception of slight right flank pain. Neurological examination also showed normal findings; her Glasgow Coma Scale (GCS) score was maximal at 15 (E4V5M6). She was ambulatory; no symptoms suggesting agnosia, agraphia, or any other higher brain dysfunction were observed on admission. In addition, finger perimetry showed no obvious visual field deficits. Laboratory findings showed a high WBC count (20,200/mm3), platelet count (40.4 × 104/mm3), and CRP level (10.02 mg/dl). Chest X-ray, abdominal X-ray, and electrocardiographic findings were normal. Urinalysis revealed pyuria with markedly increased WBCs and gram-negative bacilli, suggesting a urinary tract infection. Intravenous administration of ampicillin (6 g/day) was begun immediately after admission. On day 4, her body temperature remained higher than 38°C despite improvement in the WBC count (18,300/mm3) and CRP level (3.91 mg/dl). On the same day, E. coli was revealed in urine and blood culture specimens taken on admission. Although the E. coli was sensitive to ampicillin, we substituted ceftriaxone (2 g/day) for ampicillin on day 4 based on the results of the antibiotic sensitivity test.
Reported adult cases of brain abscess or subdural empyema owing to Escherichia coli infection
Preceding infection opportunity
Orthopedic surgery (hip), UTI
Renal cyst infection
Chronic subdural hematoma, DM
Surgical aspiration of subdural hematoma
Post-gastrectomy and splenectomy
Orthopedic surgery (leg, spine), UTI
Recent experimental hematogenous meningitis models have indicated that the primary site of entry of circulating E. coli into the CNS is the cerebral vasculature, not the choroid plexus . Nevertheless, hematogenous brain abscess formation owing to E. coli infection is rare. Bakker et al. reported that autopsy of a patient with E. coli-induced subdural empyema showed no obvious inflammation in the brain parenchyma. In our reviewed cases, seven of nine patients showed subdural empyema. These findings suggest the presence of key mechanisms preventing E. coli infection in the brain parenchyma. In an in vitro blood–brain barrier model using human brain microvascular endothelial cells (HBMECs), E. coli was shown to invade and internalize the HBMECs as membrane-bound vacuoles with no changes in the integrity of the HBMEC monolayer . Moreover, E. coli enters the CNS with no changes in the blood–brain barrier permeability and no concomitant presence of host inflammatory cells . Once E. coli invades the brain parenchyma, microglia, the resident macrophage population in the CNS, may play a key role in recognizing and eliminating the microbes via Toll-like receptors or phagocytic receptors . Additionally, activated microglia produce various pro-inflammatory cytokines, leading to the activation and chemotaxis of peripheral immune cells; however, their phagocytic or killing activity toward microbes is less potent than that of polymorphonuclear leukocytes . A recent study showed that microglia and astrocytes are specifically activated soon after bacterial invasion into the CNS parenchyma . The above findings indicate that impaired glial cell function or an impaired immune response induced by glial cells may contribute to E. coli infection in the CNS parenchyma.
Notably, a preceding E. coli infection of a simple right renal cyst might have caused the bacteremia and subsequent brain abscess in the present case. Simple renal cysts are usually observed as unilateral and solitary lesions, and the prevalence rate ranges from 7 to 10%, increasing with age . Major complications of simple renal cysts, such as hemorrhage, infection, and rupture, are rare events seen in only 2–4% of affected patients . Suwabe et al. showed that renal cysts with high intensity, a fluid–fluid level, or wall thickening on diffusion-weighted imaging suggest the presence of a cyst infection in patients with autosomal dominant polycystic kidney disease. A heterogeneous internal cyst density with no enhancement on CT also suggests a cyst infection . Symptoms of cyst infection are nonspecific. Especially in patients with autosomal-dominant polycystic kidney disease, the most conspicuous symptom is fever; in general, abdominal pain and frank hematuria are not observed . Cyst puncture and aspiration can be diagnostic and may circumvent the need for surgical procedures such as nephrectomy . Physicians should know that cyst infections may cause serious complications, even in patients with simple renal cysts.
We experienced a rare case of a brain abscess following a simple E. coli renal cyst infection. Brain abscess formation owing to hematogenous spread of E. coli is very rare. Simple renal cyst infection is also rare, but can cause serious complications. Immunosuppression may contribute to the onset of intracranial E. coli abscesses, such as brain abscesses and subdural empyema. Advanced age may also be a potent risk factor.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.
Central nervous system
- E. coli :
Glasgow coma scale
Human brain microvascular endothelial cell
Magnetic resonance imaging
White blood cell.
The authors would like to thank Dr. Jun Aoki for his assistance in preparing the radiographic images and Miss Hisae Kuribara for her secretarial assistance under the financial support provided by Social Insurance Gunma Chuo General Hospital.
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